Monday, May 16



USB 3.0 is full-duplex, catching up with serial ports of, oh, 1970 or thereabouts.

I was curious as to how close it is to PCIe 2.0.  The low-level encoding is the same (8b/10b) as is the raw speed (5Gb/s).  Beyond that there doesn't seem much detail floating around unless you download the entire specification.

So I did.

I was wondering whether the weird connectors on my new external drives* were standard or some propietary Western Digital nonsense.  Turns out they're standard micro-USB-3 connectors.  Which is good and bad; good because they're standard; bad because the standard is horrible.

Turns out USB 3, to maintain backwards compatibility with old-and-busted USB, includes old-and-busted USB.

Bearckwards compatibility....  Sorry.

That is, the cable and plugs and sockets and controllers all provide the two differential pairs for USB 3 transmit and receive (four wires total) plus the original USB 1/2 bus (two wires) plus power and ground (two wires).  Which makes the connectors twice the size (except for the standard A-type connector (the flat one) which sneakily hides the four new contacts) and the cables twice as thick.

I can understand the need to switch from a turnaround bus to a proper full-duplex point-to-point connection.  I'm surprised USB 2 even works as well as it does, having to turn around the connection constantly at 480Mb/s.

USB turnaround.

But this sort of kitchen-sink compatibility never turns out well.

On the other hand...  5Gb/s.

* Another story.

Posted by: Pixy Misa at 01:43 PM | Comments (1) | Add Comment | Trackbacks (Suck)
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1 Nice blog btw what is all about that mango photos. 
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Posted by: Kaiser at Friday, October 28 2011 06:14 PM (M4TWX)

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